Within the last two decades, cellular phones have become incorporated into almost every aspect of daily life. Cellular phones are truly ubiquitous devices which have achieved their usefulness and relatively low cost from continuing advances in modern microelectronics. As microelectronic memory densities and processing power have increased year after year, cellular phones have benefited from the commensurate availability of increasing computing power. Coupled with advances in radio frequency (RF) integrated circuits, power management microelectronics, and battery charge density improvements, the size of a typical cellular phone has been reduced to a package which fits easily in the palm of a hand.
The computational power now available in modern 3G (third generation) cellular phones rivals that of wireless personal digital assistants, so much so that there is presently almost no distinction between cellular phones, wireless communication devices targeted for email (e.g., BlackBerry™), and wireless personal digital assistants (wPDAs) (e.g. Treo™, PalmPilot™, etc.). Any device which provides bi-directional audio communication over a cellular radio network and possesses sufficient local processing capability to control the device and execute stored user applications (e.g., texting, email, calculator, web browser, games) is often referred to as a “smart phone.” The term “personal mobile communication devices” (PMCDs) more broadly comprises a class of devices which includes, but is not limited to, “smart phones,” wireless PDAs, and cellular phones, as well as other devices for communicating or processing speech which possess various degrees and combinations of embedded processing power and network connectivity (e.g., Apple™ iPhone™).
PMCDs often contain sensors and transducers by which a user interacts with the device, some of which are used for gestural interaction. An example of a transducer included in several higher-end PMCDs is the accelerometer. An accelerometer senses accelerations of the PMCD resulting from changes in kinetic forces acting upon the device as well as changes relative to the gravitational force. For instance, an accelerometer may be used to detect user gestures including physical shakes of the device, strikes of the PMCD against an eternal body, or, conversely, the strike of an external body against the PMCD. The latter events may be described as a “tap” or “hit” of the device. These user gestures can then be captured, recognized, and mapped to a specific user interface function. An accelerometer may also be used to detect if the device has been dropped or if the device's orientation with respect to gravity has changed (e.g., if the device has been tilted) or even to detect if the device has been picked up (e.g., in preparation for answering a call).
The abundant processing power, availability of user interface features, and native facilities for connecting with wireless networks, provides opportunities, therefore, to develop many new and useful applications. One such field of applications is that of music composition and performance in which PMCDs may be used to compose, transform, and play music.